Coscoroba Swan
Coscoroba coscoroba
A distinctive white swan with a bright, rather ducklike bill. The black wingtips are usually concealed when swimming. Most likely to be confused with white domestic waterfowl. Fairly common but sometimes local on lakes, slow-moving rivers, wetlands with open water, estuaries, and inshore coastal waters. Often in groups and associates readily with Black-necked Swan. Cygnets are dirty brownish with a black face mask, but young look much like adults within a month or two after hatching. Name comes from slightly gruff, honking “kós-ko roa” call.
Identification
The coscoroba swan is a medium-large sized waterfowl, but smaller than the true swans, at 90 to 115 cm (35 to 45 in) long with a wingspan of about 155 cm (61 in). Males weigh 3.8 to 5.4 kg (8.4 to 12 lb) and females 3.1 to 4.5 kg (6.8 to 9.9 lb). Their appearance is considered to be slightly unusual, being intermediate between that of geese and true swans. They have completely feathered faces—unusual for true swans—and their feet are located directly under their bodies, enabling the coscoroba swan to walk more efficiently than the “waddling” of most waterfowl. Physically, coscoroba swans have been compared to the American Pekin duck, albeit larger and with darker, redder bills and feet (Pekin ducks have bright orange bills and feet). The sexes have the same plumage; upon hatching, the chicks have blue-grey bills and feet and black striping running down the length of their bodies (to aid in camouflage from predators), with this eventually fading by about eight months of age. The adults are completely white, except for black tips to the outer six primary feathers, though this black is often barely visible on the closed wing unless the bird is in flight.
Taxonomy
The coscoroba swan's placement within the family Anatidae is not fully agreed upon, with a 2014 genetic study positing a phylogenetic relationship between this species and the Cape Barren goose (Cereopsis novaehollandiae). BirdLife International's Handbook of the Birds of the World has adopted this approach and places the coscoroba swan and Cape Barren goose together in the tribe Cereopsini, which it places as basal to Cygnus and all other geese. However, the South American Classification Committee of the American Ornithological Society, the International Ornithological Committee (IOC), and the Clements taxonomy treat the Cape Barren goose as basal to other geese, which themselves precede the coscoroba and other swans in a linear sequence. Even those three systems differ, with the IOC placing the coscoroba before Cygnus and the other two after it in their lists.<p>The coscoroba swan is the only member of the genus Coscoroba and has no subspecies.
- Scientific name
- Coscoroba coscoroba
- Authority
- (Molina, 1782)
- Order
- Anseriformes
- Family
- Anatidae
- Genus
- Coscoroba
Range and habitat
The coscoroba swan is a year-round resident of central Argentina and along the Uruguay-southern Brazil coast. It also breeds but does not winter from southern Chile and Argentina south to Tierra del Fuego and occasionally to the Falkland Islands. In winter its range extends north to central Chile, northern Argentina, Paraguay, Uruguay, and southern Brazil. It has been recorded as a vagrant in Bolivia and at several locations in Brazil north of its usual limit. The coscoroba swan inhabits well-vegetated lagoons, freshwater swamps, and sometimes human-made reservoirs. It is mainly a bird of the lowlands, though there are scattered records as high as 1,300 m (4,300 ft) and at least one at 2,000 m (6,600 ft).
- Migration
- Complete migrants
Behavior
Migration pattern: Complete migrants.
Conservation
Population trend: stable.
- Population trend
- stable
Photos
Distribution
Bird Calls
Other Birds
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